Presses



Oct- 4, 1960 H. R. GREGORY ETAL 2,954,583

PRESSES mea sept. s, 1957 51m Mm EM" *9% mm United States Patent O dustry (Patents) Limited, London, England, a British company Filed sept. s, 1951, ser. No. 681,837 Claims priority, application Great Britain Sept. 4, 1956 1 claim. (cl. 1s16) 'I'his invention relates to multiple plunger assemblies for presses,` and one object of the invention is to provide an improved plunger assembly for a press for the manufacture of briquettes without a binder from materials in divided form, .e.g. fine coal ormetallic or non-metallic powders, according to the method described in ourprior patent application No. 470,106 now Patent No. 2,860,957.

Alurthei method described in oursaid prior application a mass of Particles while under pressure is caused to undergo angular shear strain of such magnitude and distribution as to produce a briquette of high strength.

The said prior patent application also describes a method of making a briquette wherein pressure is applied to a quantity of particles to form a compacted mass and thereafter, while the mass is held under pressure, the Whole mass or an external face thereof is causedto undergo a substantial change in shape or configuration to set up within the mass angular shear strain having such magnitude and distribution as to produce a briquette of high strength. Such change in shape or configuration may be general and take place over the whole mass or over the whole of one or more external faces, e.g. by distorting the cross-section of the mass from a rectangle to a parallelogram or from 4a circle to an ellipse, or the change may be local, as for example by forming a recess or depression at some locality in an external face.

While the press plunger assembly of the present invention is envisaged as being of particular -application to the manufacture of briquettes by the method described in the above-mentioned prior patent application, it is to be understood that the invention is not limited to this application but may also be applied to the manufacture of other articles which can be made by means of a press.

In our prior patent application No. 518,308 now Patent No. 2,809,395 we have described a press having a main ram for applying the working load during the working stroke, a multiple plunger tool or assembly. having two or more relatively movable plungers for transmitting the load to the material to be treated, and a control system operated by fluid pressure derived from the reaction of the said material against the load applied by the main ram for controlling relative movement of the said plungers during the working stroke of the said ram.

Another object of the present invention is to provide an improved multiple plunger `assembly for such a press.

According to the present invention there is provided a The inner plunger may be moved in the plunger guide body by means of a huid-actuated piston, and may be spring-loaded. The outer plunger may be secured -to a cylinder which moves on the plunger guide body, the said iluid-iilled chamber being defined by the plunger guide body land the cylinder. The outer plunger may be adapted to act as a mould, and may for example` be bell-mouthed for this purpose. Further and optional features of the invention appear from the following description and claims.

In the accompanying drawing a multiple plunger assembly for a press according to the invention is illustrated by way of example. l

The illustrated multiple plunger assembly comprises a ram attachment piece 3 secured to the main ram 25 of a press. Secured to the ram attachment piece 3 is a plunger guide body 2, and a connection passage 26 communicated with a chamber 27 in the attachment piece 3. A cylinder 1 is arranged for movement on the guide body 2 and is provided with an adjustable cylindercap 4 which screws on to the cylinder and is secured by a retaining ring *14 held by screws 21. A seal 11S located by a seal support ring13 held by screws 28 is arranged to prevent leakage between the cylinder 1 and the body 2. The body 2 has an annular extension which extends into the base of the cylinder 1, and to prevent leakage here there is provided a seal 16 supported by a seal support ring 12. 'Ihe cylinder is provided with inlet and outlet passages 29 and 30 communicating with the chamber 31.

To the lower end of the cylinder 1 an annular outer plunger or mould 5 is secured by screws 19. An inner plunger 6 can move up and down in the annular extension of the body 2 and is provided with a plunger end piece 7 retained in place by a grub screw 23. A seal 18 surrounds the end piece 7 and is held in place by a retaining ring 24.

To the inner plunger 6 is secured a plunger rod 32 on 4the upper end of which an ejection piston 8 is retained by means of a nut 10 and a washer 9. The inner plunger 6 is spring-loaded by a compression return spring 11 which urges the piston 8 upwardly, `and the piston 8 is provided with a seal 17.

The body 2 is secured to the attachment piece 3 by means of screws 20, and a screw-threaded plug 22 obturates a passage leading to the chamber below the piston 8.

When the annular outer plunger 5 and the inner plunger end vpiece 7 are forced down into a lmass of particles (which may or may not be constrained Within a mould) the particles are compressed and reaction pressure gives rise to pressure in fluid in the chamber 31. When this pressure reaches ya predetermined limit a relief valve in a control system (not shown) allows oil to escape from chamber 31 so that movement of the annular outer plunger 5 ceases, 'but movement of the inner plunger 6 with its end piece 7 continues, the top end of the plunger 6 being hard up against the guide lbody 2 so that the inner plunger 6 receives practically the whole force from the main ram 25.

After the compression is completed, the main ram 25 and the multiple plunger assembly are raised. Pressure is then supplied through lthe passage 26 to the chamber 27 to force down the piston 8 and rod 32 and plunger 6 with its end piece 7 so that the 'briquette within the annular plunger mould 5 is ejected. Release of the pressure in the chamber 27 allows the plunger 6 to rise under the action of the spring 11 so that the oil reenters through connection 29 and recharges chamber 311- then assembly is ready for another operation.

The press provided with the assembly according to the invention produces a briquette of high quality because the -pressure is applied from both ends and because the "process -as kdescribed in our prior patent application No. 470,106 is carried out.

It further permits the ejection piston 8 to applya longitudinal thrust through the plunge er end piece 7 `to the briquette during its ejection. This has great virtue in permitting a radial release of strain and thus minimising the incidence of incipient cracking.

A arrangement, but may give rise to dust.

The drawing shows a plunger assembly with an anvil extractor jack or ejection piston `8 vcapable of vapplying a thrust of four tons and actuated by 'hydraulic pressure.

We claim: Y

A multiple plunger assembly for `attachment to the ram 'of a moulding press, comprising a ram attachment V"piece, a plunger guide body secured to said ram attachment piece, a piston-like enlargement on said plunger guide body, a cylinder arranged for axial movement on said piston-like enlargementon said plunger guide body, an annular outer plunger secured to said cylinder, an inner plunger arranged for axial movement within said plunger guide body, a plunger-end-piece secured to said s -4 l inner plunger and arranged for axial movement within said outer plunger, an ejection piston secured to said inner plunger and tting slidingly in a chamber in said ram attachment piece, and a spring Within said chamber acting on said ejection piston to Withdraw said inner plunger further into said outer plunger, said cylinder and said chamber being provided with passages for the supply and escape ofuid under pressure, the arrangement being such that during Vmoulding said inner plunger abuts said plunger guide body and thereisdirecttransmission of force through said ram attachment piece, said plunger guide body and said inner lplunger and said plunger end-piece to material within said outer plunger, and after moulding l.fluid under pressure admitted to said chamber Vacts on said ejection plunger in opposition to said spring 'for ,movingjsaid innerrplunger outwardly in said outer plunger.

References Cited in the le of this patent UNITED `S'LTI-ES PATENTS 1,526,788 Henman Feb. 17, 1925 '2,488,581 vCherry'et al. `Nov. 22, 1949 2,608,826 II-Ialler Sept. 12,- 19,52 2,809,395 Gregory et al.. Oct. '15,1957

` FOREIGN PATENTS 927,283 France Oct. .24, 1947 

